Cloudera Docs

Debugging Impala Virtual Warehouses

You can use the Catalog Web UI, Coordinator Web UI, and the StateStore Web UI to debug Impala Virtual Warehouses in Cloudera Data Warehouse (CDW).

Table level events

In addition to global metrics described below, the following table metrics are available for debugging an Impala Virtual Warehouse:
  • avg-events-process-duration
  • events-consuming-delay-ms

avg-events-process-duration metric

This metric represents the sum of the time for processing all events. This metric is helpful to identify the average duration of processed events on the table and to identify which tables are causing the event-processor to lag behind. As a temporary workaround, you can disable event processing on that table. You can set the metric collection period to 1 minute, 5 minutes, and 15 minutes duration:
  • avg-events-process-duration-1min-rate

    Exponentially weighted moving average (EWMA) of number of events processed in last 1 min

  • avg-events-process-duration-5min-rate

    Exponentially weighted moving average (EWMA) of number of events processed in last 5 min

  • avg-events-process-duration-1min-rate

    Exponentially weighted moving average (EWMA) of number of events processed in last 15 min

Metric output looks something like this:

events-consuming-delay-ms metric

This metric represents the time difference between creating an event in the metastore and processing an event. Using this metric, you can gauge how long the event processor is lagging.

Metric output looks something like this:

The Impala daemons (impalad, statestored, and catalogd) debug Web UIs, which can be used in CDP Runtime by using Cloudera Manager, is also available in the CDW service. In CDW service, the following Web UIs are provided:

  • Impala Catalog Web UI

    This UI provides the same type of information as the Catalog Server Web UI in Cloudera Manager. It includes information about the objects managed by the Impala Virtual Warehouse. For more information about this debug Web UI, see Debug Web UI for Catalog Server.

  • Impala Coordinator Web UI

    This UI provides the same type of information as the Impala Daemon Web UI in Cloudera Manager. It includes information about configuration settings, running and completed queries, and associated performance and resource usage for queries. For information about this debug Web UI, see Debug Web UI for Impala Daemon.

  • Impala StateStore Web UI

    This UI provides the same type of information as the StateStore Web UI in Cloudera Manager. It includes information about memory usage, configuration settings, and ongoing health checks that are performed by the Impala statestored daemon. For information about this debug Web UI, see Debug Web UI for StateStore.

  • Impala Autoscaler Web UI

    This UI gives you insight into Autoscaler operations, accessing log messages, and resetting the log level. The autoscaler Web UI includes information about the queries queued and running, executor groups, suspended calls, scale up/down calls, the autoscaler config, and the autoscaler logs.

Required role: EnvironmentAdmin

  1. In the CDW UI on the Overview page, locate the Impala Virtual Warehouse for which you want to view the debug UIs, and select Edit from the options menu on the tile. This launches the details page for this Virtual Warehouse.
  2. In the Virtual Warehouse details page, select the WEB UI tab on the right. The list of debug Web UI links are displayed as shown in the following image:


  3. Click a Web UI link corresponding to an Impala daemon that you want to debug.
    You are prompted to enter your workload user name and password.
After you are authenticated, you can view the debug Web UI and use the information to help you troubleshoot issues with your Impala Virtual Warehouse.